The biological characteristics of Smerinthus planus Walker

Smerinthus planus Walker has 2 generations every year in Xining,their pupa overwintered in the soil of 5～10 cm depth.Adults emerge in May of the next year and the peak of occurrence appeared in June.Adults of the first generation emerge in the third ten days of July and the peak of emergence appeared from the second ten days of August to the first ten days of September,their longevity reached 30 d.Eggs were oviposited dispersively on the shadow side of young stick or branch of the tree.The lasting time of development of egg,larva,pupa is 8,37,20d respectively.Larva had 5 instars and ate 160 leaves off during all larval stage.The heavier damage stage among each year was from July to August caused by larvae of the first generation.